I was definitely a neurotic freshman and there's nothing wrong with being worried and planning for your goals now- as long as you aren't allowing yourself to get freaked out or drawing conclusions yet (I.E. "I got one B freshman year. Am I screwed forever???"). The best thing I did freshman year (also a small liberal arts college) was start going to office hours right away and developing a relationship with my professors. Sure, I probably seemed a little over-eager and concerned, but they were all super helpful with study tips, general discussions of the subject, and personal stories about their experience. You know you need to try your hardest to earn whatever GPA and MCAT score you can. And as you go, people here can help advise you, but make sure to talk to your academic support center and pre-med advisors first
Also
@gyngyn 's advice to treat college like work is spot on. You have a ton of free time outside of class. If you make it a 9-5 (or equivalent) work schedule, it's easier to stay on top of everything